Dry-cargo marine containers come in many sizes, e.g., 20, 40, 45, 53 feet in length, typically rectangular or box-like, designed to be stacked one upon another according to ISO 1161 standard, for example. More specifically, ISO class containers come in following sizes: 20xe2x80x2 (length)xc3x978xe2x80x2 (width)xc3x978xe2x80x26xe2x80x3 (height); 40xe2x80x2xc3x978xe2x80x2xc3x978xe2x80x26xe2x80x3; and 40xe2x80x2xc3x978xe2x80x2xc3x979xe2x80x26xe2x80x3 (Hi cube). Domestic class containers come in following sizes: 45xe2x80x2xc3x978xe2x80x26xe2x80x3xc3x979xe2x80x26xe2x80x3 and 53xe2x80x2xc3x978xe2x80x26xe2x80x3xc3x979xe2x80x26xe2x80x3. Referring to FIG. 1, a conventional container 10 of this type has a base assembly 12, four vertical corner posts 16 extending vertically from four lower corner fittings 14, two upper side and two upper cross beams 18 connected together to the four corner posts 16 via four upper corner fittings 20. The corner posts 16 extend between each pair of container""s four upper and lower corner fittings 20, 14. The base assembly includes a floor panel (not shown) supported between a pair of lower side beams 18xe2x80x2 and a pair of lower of cross beams 18. These beams and posts are typically made of bent sheet metal angles and channels.
The container(s) stacked above are designed to sit on the top four corner fittings 20 so that it, with the respective four corner posts 16, transmits weight to the bottom four corner fittings of the base assembly and to any internal frame at the front and rear sides.
The container of this type further includes a roof panel 22, two longitudinal side panels 24, a front assembly and a door assembly, and the floor. The side panels 24 generally support the roof and any objects resting or accumulated thereon, such as snow or ice. The container(s) stacked above is not designed to exert downward load on the roof or the four side panels. Thus, the side panels are not under compression from top to bottom. They, however, do act as diagonal braces to the frame since the side panels are welded to the side and cross beams 18, 18xe2x80x2, and the corner posts 16 at their four edges.
Typically, each of the panels 22, 24 is formed from a plurality of corrugated sheets of commercial quality steel joined side-by-side by welding so that the joined seams run generally perpendicularly to the length of the panel. See FIG. 2. FIG. 1 shows the corrugation 30 more clearly. The corrugation, which is necessary to add strength or rigidity to the panel, are typically formed by a brake press.
Referring to FIG. 2, a plurality of corrugated steel sheets are butt welded side-by-side using traditional wire fill arc-welding techniques. This welding is slow and difficult to automate. Further, the arc-welding technique and the butt welding construction require a thicker panel than would be normally required for other types of welding.
Each side panel is welded to the horizontally extending side beams 18, 18xe2x80x2 at their upper and lower corrugated edges. Specifically, during the following framing operation, the side panels are hung vertically while the undulating bottom edge is welded to the lower side beams 18xe2x80x2 using conventional arc welding techniques. See FIG. 10C. This welding is slow and difficult to automate because of the undulating nature and lack of dimensional uniformity of the corrugation, and the poor fit-up to the base assembly 12. Moreover, the manufacturing tolerance variations generated with the conventional cargo container designs and manufacturing processes make the automatic welding and assembly even more difficult. Further, because the panel has to be arc-welded or has butt welding construction or both, the panel has to be thicker than necessary, wasting material.
There is a need to automate cargo container assembly without the aforementioned drawbacks. The present invention meets this need.
The present invention relates to a non-corrugated panel and a method of forming the panel, which can be used to make a stackable container. Another aspect of the invention is a container constructed of the present panel. Each of the panel has flat portions along the edges, with longitudinally spaced apart reinforcing ribs, which extend substantially along the entire width or height of the panel. Spacing is provided between the two long edges and the longitudinal ends of the ribs so that at least the two long edges remain flat therealong. This makes welding easy and economical. Of course, it is preferable to make the other two ends with flat portions too.
Specifically, a metal panel according to the invention comprises first and second elongated metal sheets each of a predetermined width. The first and second sheets are positioned side-by-side and overlapped by a predetermined amount. The overlapped area is then welded, preferably by mash seam or CO2 laser welding. Reinforcing ribs are formed, longitudinally spaced and extending substantially perpendicularly to the longitudinal direction of the joined metal sheets. The ribs end before the outer edges of the first and second joined metal sheets to provide four welding portions, each of a predetermined width, such as xc2xdxe2x80x3 to 1xe2x80x3 for example, having a flat continuous welding area along the respective edge.
The ribs can all extend in one direction and are preferably spaced apart by an approximately equal amount.
A cargo container according to the invention comprises a frame assembly having a floor panel, a front panel, two side panels, a door panel, and a roof panel all connected to the frame assembly preferably by welding. At least one of the front panel, the two side panels, and the roof panel has a reinforced panel construction as described above. Preferably, each of the side and roof panels has the reinforced panel construction. The front and door panels, as well as the floor panel can all have the reinforced panel construction.
The frame assembly preferably comprises a base assembly, a pair of spaced apart upper side beams, a pair of spaced apart upper cross beams, and four corner posts connecting the base assembly to the upper side and cross beams. The base assembly includes a pair of lower side beams each having a flat vertical portion and a pair of lower cross beams.
One of the four flat welding portions of each side panel is welded to the vertically flat portion of one of the lower side beam and the remaining three welding portions are welded to one of the upper side beams and two vertical posts connected to that side beam. The roof panel is welded to the upper side beams and upper cross beams. The reinforcing ribs of the side panels extend preferably into the container and the reinforcing ribs of the roof panel extend preferably upwardly and outwardly.
According to the invention, at least one of the upper and lower side and cross beams is tubular. Preferably, all of the beams and all of the corner posts are tubular. The tubular beams can be rectangular or L-shaped welded sheet metal tubing. For example, the front corner posts can be the L-shaped tubing and the upper and lower side and cross beams can be rectangular tubes.
A method of forming a panel comprises providing first and second elongated metal sheets each of a predetermined width and an indefinite length; positioning the first and second sheets side-by-side; overlapping adjacent longitudinal edges of the first and second sheets by a predetermined amount to form a lapped area; welding the lapped area to form a panel blank of an indefinite length; cutting the panel blank to a predetermined length; and forming a plurality of elongated reinforcing ribs extending substantially perpendicularly to the longitudinal direction of the panel and leaving four flat welding portions near along the four edges of the panel.
Preferably, the panel blank is cut to the predetermined length before forming the reinforcing ribs. Although each of the four flat welding portions can be made to any dimension, it preferably has at least a xc2xdxe2x80x3 width running along the peripheral edge of the panel. The welded seam is then preferably flattened, using for instance, planish rolls.
A method of forming a container comprises a) providing a container frame having a base assembly, a pair of spaced apart upper side beams, a pair of spaced apart upper cross beams, and four corner posts connecting the base assembly to the upper side and cross beams; b) providing two side panels each having four flat welding portions for bracing against the upper side beam, two corner posts and the base assembly; c) securing one of the side panels against the upper side beam, the two corner posts, and the base assembly; d) mash seam or CO2 laser welding the four flat welding portions to the upper side beam, the two corner posts, and the base assembly; and e) repeating acts c) and d) for the other side panel.
A roof panel having four flat welding portions formed around the perimeter can also be secured to the upper side beams and upper cross beams. Then, the welding strips can be mash or CO2 laser seam welded to the upper side and cross beams. According to the invention, the mash or CO2 laser seam welding can be automated.
A container made according to the invention is suitable for all current standard sizes of ISO and Domestic dry cargo, open top, ventilated, reefer (refrigerating) containers, and atmospherically controlled container for organic and inorganic goods.